diff --git a/AABB_tree/demo/AABB_tree/CMakeLists.txt b/AABB_tree/demo/AABB_tree/CMakeLists.txt
index 67aa9ff64a1..11a5922ccf6 100644
--- a/AABB_tree/demo/AABB_tree/CMakeLists.txt
+++ b/AABB_tree/demo/AABB_tree/CMakeLists.txt
@@ -16,11 +16,6 @@ if(POLICY CMP0071)
   cmake_policy(SET CMP0071 NEW)
 endif()
 
-if( (${CMAKE_CXX_COMPILER_ID} STREQUAL "GNU") AND
-    (${CMAKE_CXX_COMPILER_VERSION} VERSION_GREATER "9" OR ${CMAKE_CXX_COMPILER_VERSION} VERSION_EQUAL "9") )
-  set(CMAKE_CXX_FLAGS "-Wno-deprecated-copy  ${CMAKE_CXX_FLAGS}")                          
-endif()
-
 # Include this package's headers first
 include_directories( BEFORE ./ ./include )
 
diff --git a/Installation/cmake/modules/CGAL_SetupCGAL_Qt5Dependencies.cmake b/Installation/cmake/modules/CGAL_SetupCGAL_Qt5Dependencies.cmake
index 2ab430f9200..37903ecbbb7 100644
--- a/Installation/cmake/modules/CGAL_SetupCGAL_Qt5Dependencies.cmake
+++ b/Installation/cmake/modules/CGAL_SetupCGAL_Qt5Dependencies.cmake
@@ -118,5 +118,13 @@ function(CGAL_setup_CGAL_Qt5_dependencies target)
     target_link_libraries( ${target} ${keyword} CGAL::Qt5_moc_and_resources)
   endif()
   target_link_libraries( ${target} ${keyword} Qt5::OpenGL Qt5::Svg Qt5::Xml)
+
+  # Remove -Wdeprecated-copy, for g++ >= 9.0, because Qt5, as of
+  # version 5.12, has a lot of [-Wdeprecated-copy] warnings.
+  if( CMAKE_CXX_COMPILER_ID STREQUAL "GNU"
+      AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS "9" )
+    target_compile_options( ${target} ${keyword} "-Wno-deprecated-copy" )
+  endif()
+
 endfunction()